A conventional image forming apparatus including a copying machine, a printer and a facsimile uses an electrophotographic system. In the conventional image forming apparatus, a sheet, for which a toner image thermal fixing process has been finished, is curled. Thus, a curl correction roller for removing the curl is usually provided. There is one curl correction roller in which, along the periphery of a large-diameter correction roller, two rollers having a smaller diameter than the correction roller are located side-by-side and abutted against the correction roller (for example, refer to JP-A-7-179258). By this means, between the abutments of the two rollers with the correction roller, the sheet is conveyed along the periphery of the correction roller, whereby the curl is corrected by the curvature of the correction roller.